All CEUS imaging will be performed using the dual B-mode (used to locate anatomical features) and nonlinear contrast (to identify the ultrasound contrast agent) imaging mode. A low mechanical index (< 0.1) will be used to minimize microbubble destruction during imaging. The standard nonlinear imaging frequency pairings in the contrast imaging software will be used (transmitting at 2 MHz, receiving at the 4 MHz harmonic), and gain settings will be adjusted to minimize nonlinear signals prior to contrast injection. Additionally, the focal zone will be placed at the approximate depth of the lesion to maximize the generation of nonlinear signals during CEUS. During the first contrast injection, 2D CEUS will be performed using the coded harmonics nonlinear imaging package on the unit. The approximate tumor mid-line will be imaged until homogenous liver enhancement is achieved (approximately 45 seconds post injection), followed by imaging sweeps through the tumor. Sweeps will then be acquired in the sagittal plane, before returning to the original plane. Imaging will be continued until contrast washout is observed (approximately 3-4 minutes), after which data will be digitally stored for later review. A fifteen minute wait period will be observed between injections to allow for complete ultrasound contrast agent clearance. A region of interest encompassing the entire tumor volume and margin will then be selected in 4D mode. Baseline imaging of the tumor will be repeated in 4D mode in grayscale B-mode. A second bolus injection of up to 0.6 ml Definity followed by 10 cc saline flush will again be administered during continuous tumor imaging in 4D, which uses the machine's coded harmonics package. Data will be obtained until contrast washout is observed and then digitally stored in digital imaging and communications in medicine (DICOM) format for later review.